112 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
like process, which is longer than that of A. torquata (Fig. 2). 
The dorsal and lateral margins of the head are prolonged into a 
thin rim, which shows three small notches (PL 1, Fig. 3), a median 
dorsal one and a pair of much smaller ones so situated as to divide 
each lateral half rim into two unequal portions, a posterior dorsal 
third, and an anterior ventral two thirds. A large number of ocelli, 
more than a hundred, are found on the anterior ventral surface of 
this first segment, just in front of the mouth (PI. 1, Figs. 4, 5). 
They show a somewhat Y-shaped arrangement, and in preserved 
specimens have the appearance of very small brownish black dots, 
visible only with the aid of a lens. 
In the remaining thoracic segments there are setae, which are 
borne near the anterior end of the segment (PI. 1, Fig. 1). 
The abdominal segments, five in number, show a nearly uniform 
diameter throughout their length. The setae of the first four are 
placed near the posterior end of the anterior third of the segment 
(pi. i. Fig. 1). The first two abdominal segments are of about 
equal length; the third is slightly longer than the second; the 
fourth is longer than the third, and is followed by a segment which 
is much shorter than any of the other four. In this short abdomi¬ 
nal segment the setae are placed at the middle of the segment. 
The boundary line between this and the first segment of the tail is 
very inconspicuous. 
The collar, which is formed by the forward prolongation of the 
anterior margin of the first abdominal segment, is not well marked. 
With the beginning of the third portion of the body there is an 
abrupt change in the position of the parapodia. Throughout the 
tail region these are borne very near the posterior ends of the 
segments. Behind the fifth segment of the tail there is a continual 
decrease in the length of the segments, until the posterior end of 
the animal is reached. The worm is easily broken in this third 
region; this, no doubt, accounts for the difficulty of getting entire 
specimens. 
The preanal # segment (PI. 1, Fig. 6) is very short and destitute 
of both setae and uncini. The anal segment is surrounded by a 
circle of papillae much as in A. torquata; but in A. torquata the 
three segments in front of the anal segment are destitute of setae. 
The dorsal setae (PI. 2 , Figs. 16, 17) are long and slender, of 
capillary fineness, and become very abundant in the abdomen and 
anterior segments of the tail, There are two forms, both of which 
